Friis Transmission Calculator

Pasternack's Friis Transmission Equation Calculator will calculate the received power from an antenna at some distance given a transmission frequency and antenna gains.

Note:  Equation 1 below uses linear power units (mW/W), while Equation 2 uses dBm/dBW.




Received Power:

Friis Equation is used to find the ideal power received at an antenna from basic information about the transmission. The only inherent pitfall of Friis equation is the fact that it is only calculated for a single frequency, where transmissions are typically comprised of many. However, given a high enough center frequency, the difference in received power over the bandwidth should be reasonably small.

Prefix Symbol Value
Tera 'T' 1012
Giga 'G' 109
Mega 'M' 106
kilo 'k' 103
Prefix Symbol Value
pico 'p' 10-12
nano 'n' 10-9
micro 'u' 10-6
milli 'm' 10-3